Phase-conjugate interferometry for thin film analysis

A phase-conjugate interferometric method of thin film analysis obtains three independent parameters with which to determine a film's refractive index n, absorption coefficient kappa, and thickness d. Because dimensionless intensity ratios are used, this method is self-calibrating except for light source polarization and incident angle. The use of self-pumped phase-conjugate reflectors makes the interferometer self-aligning and results in infinite spacing of fringes of equal thickness. A single layer thin film sample was analyzed by this technique, and the results compared to those of ellipsometry